((output
  (((f.ml (1 0) (1 10))
    (paragraph
     (((f.ml (1 0) (1 10)) (emphasis (((f.ml (1 6) (1 9)) (word foo))))))))))
 (warnings
  ( "File \"f.ml\", line 1, characters 3-4:\
   \nIdentifier in reference should not be empty.")))